Air-conditioners, dehumidifiers and other climate control systems circulate air over a cooler surface. The evaporator cooling coil of an air conditioner, for example, condenses water from the humid air and this condensate generally drains and collects in a pan which is connected to the outdoors by a drain line. The temperature, humidity, and general environment of the condensate pan is favorable for the growth of microbes. These growths can clog the drain lines and result in flooding of the adjacent area (since the condensate pan has a free surface open to the air, which can overflow).
During winter months, humidifiers are sometimes used to humidify dry air by passing dry air across a moist surface. Systems such as pan humidifiers, power wetted-element humidifier, atomizing humidifiers, ultrasonic humidifiers, and rigid media humidifiers are common. A humidifier by nature requires a water source which is evaporated into the dry air. To avoid the build-up of non-volatile solids (such as calcium and other minerals) as the water is evaporated from the humidifier, excess water is supplied to the humidifier, requiring a humidifier drain line to transport the remaining excess water and non-volatile solids that could not otherwise evaporate. The water draining from these systems can develop microbial colonies which can clog the drain line and thereby flood the area adjacent to the humidifier (since the humidifier also has a free surface open to the air, which can overflow).
Treating the condensate water contained in the condensate pan has the additional advantage of removing microbes entrained by the circulating air of a climate control system. One way to eliminate these microbes is to open the system and place a biocide tablet directly in the condensate drain pan or humidifier. This is accomplished by removing access panels and insulation to gain access to the condensate pan (in the case of an AC systems) or the humidifier reservoir. However, it is usually not a trivial matter to open and close a climate control system such as an air-conditioner air handling unit or forced-air furnace. While the treatment of the microbial growths directly in the condensate pan of an air conditioner would be ideal, a simpler location would be to treat the drain line as the condensate water exits the air handler or humidifier. This is an easer location to access. The present invention involves an improved device for treating the water as it exits the air handler or humidifier, without the need to open any access panels or disassemble any systems.
The presents invention treats the water contained in the condensate pan by the use of a dispenser located immediately downstream of the condensate drain, i.e., the microbial growths are treated directly in the condensate pan of an air conditioner or humidifier from an adjacent downstream location and without opening up the system or removing access panels. In one embodiment of the present invention, the water trapped in the dispenser communicates with the water retained in the condensate pan (the trapped and retained water are at the same elevation), thereby allowing diffusion of the biocide chemicals from the dispenser into the condensate pan of the A/C unit (or into the humidifier), without requiring access to the condensate pan to introduce the biocide directly into the pan.
The treatment of the microbe laden water can be accomplished using an automatic time-released or long duration method. For example. one tablet or packet could reduce bacteria, fungi, algae, and mold in a water reservoir for an entire summer (e.g., about 3 months or longer). Metals such as silver (Ag), nickel (Ni), zinc (Zn), and copper (Cu) are known in the art as effective biocides. For example, Ag is effective against virus and bacteria. In particular, a concentration of about 0.02 ppm (or 20 ppb) in water is effective against Legionella pneumophilia. Cu is also an effective algaecide and in some cases a bactericide. Other metals can also be effective against different microbes to differing degrees. This time release technology is more completely described by U.S. Pat. No. 6,303,039B1 to Back, et. al. Metals such as these used as a biocide are typically provided in water-soluble form. Hence, these materials are generally added to water systems as a water soluble salt. In order to extend the biocidal efficacy of these highly soluble salts over an extended period of time, the compounds must be metered into the water mechanically or added manually on a schedule. An external dispenser would allow the equipment owner, instead of the service technician, the ability to add the biocide, since no knowledge of the way (or the tools and skills necessary) to remove the access panels to gain access to the condensate pan would be required. Prior to the present invention, these external in-line chlorinators had no capability to treat the water upstream in the condensate pan or humidifier. Such an in-line chlorinator is disclosed in U.S. Pat. No. 5,402,813 to Keen and sold under the “AL-G-Gator” name. U.S. Pat. No. 5,402,813 also discusses the use of additional “water-leachable algicide” that “preferably includes an ingredient which gradually releases chlorine to a flowing stream of water.” Two time release tablets; are specifically mentioned namely PACE®, a registered trademark of Olin Corporation and 2,000 Flushes®, a registered trademark of Block Drug Company. We have found that the time-release method disclosed by in U.S. Pat. No. 6,303,039B1 is preferred to the time-release products disclosed in U.S. Pat. No. 5,402,813.
The cost of manufacturing a time-release biocide is significantly more expensive that simply using common liquid chlorine beach used everyday by homeowners. One object of the present invention is to develop a dispenser which can be located in a convenient location for equipment owner access, so that a professional technician is not required for using the dispenser, and to configure the dispenser with a wide-mouth to simplify the pouring of common household bleach into the dispenser.
Another object of the present invention is to develop a dispenser which will allow both the immediate and gradual release of a liquid biocide, including common household liquid bleach.
I have discovered that while there is biological growth in the condensate water from an air-conditioning system (or humidifier drain line), and therefore on any surface in contact with this water, the only instances where this growth can result in flooding of the building, is when the growth blocks the flow of water in the drain line. The flow of water in these drain lines is due to the effects of gravity only, therefore there is only the elevation head of the water which supplies the pressure needed to establish a flow rate or dislodge a clog.
I have also discovered that, if the drain line is properly installed, there is one specific location in the drain line where the clog will occur, namely the condensate liquid trap. A liquid trap is a U-section of plumbing that is installed in a (gravity-induced flow) plumbing line to seal off the plumbing when there is no water flow (a low point in the plumbing located below both the inlet and outlet). For a gravity-driven water flow, when the flow stops, water is trapped in the U-section of a liquid trap, since both the inlet and outlet are located at a higher elevation. This trapped water seals the pipe. In a sewage line, the liquid trap acts as a vapor barrier to kee sewers gases from entering the house, whereas in an HVAC condensate line (or humidifier drain line), the liquid trap serves as a inset barrier to prevent insects, bugs and the like from traveling from the outside of the house through the drain line and into the HVAC system of the building. Since this liquid trap always contains stagnant water, it represents the location were a plumbing clog due to biological growth will occur. Column 3 of above-mentioned U.S. Pat. No. 5,402,813, he states that the “in-line algicide dispenser is inserted in the condensation line or drain as close to the air-conditioner, icemaker, or other appliance as possible. Stated in slightly different terms, the water-leachable algicide is disposed in the flowing stream of condensate as far upstream as possible.” I have found that it is unnecessary to locate the dispenser as far as possible upstream; rather it only needs to be upstream of the liquid trap. Furthermore, it is far better to install the in-line dispenser in the most convenient location for access by the untrained equipment owner or homeowner. That is, the dispenser should be located where it is convenient for the equipment owner to easily access the dispenser and add household liquid bleach or time release tablets, as long as it is located upstream of the condensate trap. Since the condensate trap is typically located outdoors at the very end of the condensate line, the liquid dispenser can also be located outdoors, which may prove to be convenient for adding household liquid bleach or time-release tablets.
Still another object of the present invention is to improve the dispenser shown in U.S. Pat. No. 5,402,813 to Keen by using a wide mouth dispenser to simplify the pouring of ordinary household liquid bleach into the dispenser.
Another object of the present invention is to improve the known dispenser by using a contained volume which provides erosion protection for the solid biocide, retains the solid biocide in the dispenser (to avoid the solid biocide from clogging the outlet), and in the case of a liquid biocide provides for a gradual release (by dilution with condensate water) of some liquid biocide trapped in the contained volume.
I have found that a time-release or the otherwise “gradual release of chlorine” as discussed by at Column 2, lines 51 et seq. of U.S. Pat. No. 5,402,813 is not necessary to prevent drain line clogging. In addition to the significant cost differential between time-release tablets and ordinary household bleach, I have also found that introducing household chlorine bleach periodically is sufficient to prevent line clogging and that it is not necessary for a time-released introduction of chlorine into the condensate drain line. As stated above however, I have developed an effective way to provide some level of time-release action.
I have recognized that the biological growth that occurs in the condensate drain line's liquid trap, is only a problem once it has become sufficient to actually clog the line. Therefore, rather than continually killing any growth as it occurs, it is only necessary to kill any growth before it completely clogs the condensate line. While the time to actually clog a drain line is dependent on the nutrients in the water, the water temperature, and the microorganisms present, the time for such grown is on the order of 6 to 12 months, therefore a periodic introduction of liquid bleach (for example, once at the beginning of the cooling season in the northern climates) and quarterly in the southern climates is more than sufficient.
The avoidance of flooding due to biological growth which clogs the condensate drain line is not to be confused with the effect of biological growth on the evaporator coils, condensate drain pain or humidifier (which are exposed to conditioned air). Growth on these surfaces should be minimized by the use of biocide treatment tablets, as disclosed by above-mentioned U.S. Pat. No. 6,303,039B1, to avoid the entrainment of such biological contaminates into the air being breathed by inhabitants of the building, especially if such occupants have allergies to mold or fungi. However, a dispenser in the condensate or humidifier drain line, which is downstream of these surfaces will typically have no effect on biological growth upstream. However, the present invention also contemplates an embodiment where the biocide in the dispenser, located downstream and adjacent to the condensate drain, will allow biocide to diffuse into the condensate pan or humidifier.
Therefore, to summarize, the present invention provides an improved dispenser for the simple periodic treatment of clogged condensate lines by untrained equipment owners. Moreover, the present invention also provides a device which, when utilized and correctly located, will also allow the introduction or liquid or solid biocides into the condensate pan of AC units or into hot-air furnace humidifiers where the biocides improve indoor air quality in addition to killing microorganisms that might clog drain lines. Prior to the present invention, the introduction of biocides into drain pans and furnace humidifiers had required the services of a skilled HVAC/R technician to introduce the biocide multiple times per year.